Previous research has found signs of igneous rock on Vesta, indicating that rock on Vesta's surface was once molten, a sign of differentiation.

If the troughs derive from differentiation, then they're graben - a dip in the surface that forms when two faults move apart from each other and the ground sinks into the widening gap. Death Valley in California is one example.

And the images from the Dawn mission show that Vesta's troughs have many of the qualities of graben, such as floors that are flat or curved and have distinct walls on either side, like the letter U.

Vesta now appears to be unusually planet-like, in that its mantle is ductile and can stretch under a lot of pressure. "It can become almost silly putty-ish," said Buczkowski. "You pull it and it deforms."